Example 1311 Local SRB Configuration

interface TokenRing0

no ip address no ip directed-broadcast ring-speed 16

multiring all source-bridge 1 1 2

interface TokenRing1 no ip address no ip directed-broadcast ring-speed 16

RIF enabled From ring 1 thru bridge 1 to ring 2

multiring all

source-b

RIF enabled From ring 2 thru bridge 1 to ring 1

Configuring Multiport Local Source-Route Bridging

The other type of SRB is needed when there are more than two Token Ring interfaces to bridge between. This type of configuration requires a virtual ring to be defined on the router. A virtual ring is just as the name describes, a virtual entity that connects two or more physical rings locally or remotely. A virtual ring also is referred to as a ring group. As you will see in the next section, "Configuring Remote Source-Route Bridging," a virtual ring can span an entire IP domain. For now, the virtual ring will be limited to the local router. Figure 13-17 contains an example of a three-port SRB. To configure SRB between rings 1, 2, and 10, you will need to configure a virtual ring. Then, you will source-bridge every real Token Ring to the virtual ring. Figure 13-18 illustrates conceptually how the network will look with the location of the virtual ring.

Figure 13-17. SRB Multiport Bridging

Figure 13-17. SRB Multiport Bridging

Figure 13-18. SRB Multiport Bridging Conceptual View

To configure this type of SRB, follow this four-step process:

Step 1. Define a virtual ring on the router. This is accomplished with this global router command:

Router(config)#source-bridge ring-group virtual_ring_number

The virtual ring number can range from 1 to 4095.

Step 2. Enable the use of the RIF, if required, with the router interface command multiring all. The full syntax is as follows:

Router(config-if)#multiring {protocol-keyword | all | other} no multiring {protocol-keyword | all | other}

Step 3. Configure SRB for the Token Ring interface. This is accomplished with the following interface command:

Router(config-if)#source-bridge local_ring brldge_number virtual_ring

Step 4. (Optional) Enable Spanning Tree explorers. By doing so, you can reduce the number of explorers that transverse the network. NetBIOS and NetBEUI require Spanning Tree explorers to function properly. Cisco recommends enabling Spanning Tree explorers in complex multiprotocol networks. To enable them, use this interface command:

Router(config-if)#source-bridge spanning

Example 13-12 shows the configuration for local multiport SRB for the network in Figure 13-17. Example 13-12 Multiport SRB Configuration source-bridge ring-group 100 Configure a virtual ring of 100

interface TokenRingO

no ip address no ip directed-broadcast ring-speed 16

multiring all 1 BIF enabled source-bridge 1 2 100 From ring 1 thru bridge 2 to V-ring 100

interface TokenRing1 no ip address no ip directed-broadcast ring-speed 16

multiring all * RIF enabled source-bridge 2 2 100 From ring 2 thru bridge 2 to V-ring 100

interface TokenRing2 no ip address no ip directed-broadcast ring-speed 16

multiring all RIF enabled source-bridge 10 2 100 ■ From ring 10 thru bridge 2 to V-ring 100

Configuring Remote Source-Route Bridging

SRB also can be configured to span a single WAN serial interface or an entire IP domain. This type of configuration is called remote source-route bridging (RSRB), which involves defining a virtual ring to link the remote bridges. Figure 13-19 illustrates a Token Ring SRB network connected by a common Frame Relay network.

Figure 13-19. RSRB Network Connected by a Frame Relay Network

Figure 13-19. RSRB Network Connected by a Frame Relay Network

To configure RSRB, you need to define a common virtual ring to connect all the SRBs. The most logical spot for the virtual ring is the IP network, or the WAN, in this example. Figure 13-20 illustrates the RSRB with the virtual ring defined.

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